The earliest known use of "Black Friday" to refer to the day after Thanksgiving occurred in the journal, Factory Management and Maintenance, for November 1951, and again in 1952. Here it referred to the practice of workers calling in sick on the day after Thanksgiving, in order to have a four-day weekend. However, this use does not appear to have caught on. Around the same time, the terms "Black Friday" and "Black Saturday" came to be used by the police in Philadelphia and Rochester to describe the crowds and traffic congestion accompanying the start of the Christmas shopping season. In 1961, the city and merchants of Philadelphia attempted to improve conditions, and a public relations expert recommended rebranding the days "Big Friday" and "Big Saturday", but these terms were quickly forgotten.[7][8][9][10][11][12]